Method for the preparation of ethylene polymer composition

ABSTRACT

In accordance with the present invention, there is provided a method for the preparation of an ethylene polymer composition having a density of 0.86-0.94 g/cm 3  and an intrinsic viscosity [η] of 1-6 dl/g using an olefin polymerization catalyst composed of a transition metal compound containing a ligand having a cycloalkadienyl skeleton and an organoaluminium oxy-compound, and there is also provided a method for the preparation of an ethylene polymer composition having density of 0.87-0.93 g/cm3 and an intrinsic viscosity [η] of 0.5-6 dl/g.

This application is a continuation of application Ser. No. 07/654,031,filed Feb. 12, 1991, now abandoned.

FIELD OF THE INVENTION

This invention relates to a method for the preparation of ethylenepolymer compositions, particularly to a method for the preparation ofethylene polymer compositions by multi-stage polymerization, and moreparticularly to a method for the preparation of ethylene polymercompositions which are excellent in melt properties and favorable inprocessability at the time of melt molding.

The invention also relates to a method for the preparation of ethylenepolymer compositions which are small in amount of their hydrocarbonsolvent-soluble portion in spite of their having a low density andaccordingly excellent in anti-block properties and also heat resistance.

BACKGROUND OF THE INVENTION

Recently, methods for the preparation of olefin polymers using acatalyst composed of a zirconocene compound and aluminoxane as a newtype of Ziegler olefin polymerization catalysts have been proposed, forexample, in Japanese Patent L-O-P Publns. Nos. 19309/1983, 35007/1985and 221208/1986. According to these publications cited above, it isreported that ethylene polymers having a narrow molecular weightdistribution and a narrow composition distribution and excellent intransparency are obtained. However, the polymers obtained by the use ofsuch olefin polymerization catalysts as mentioned above have a narrowmolecular weight distribution and are poor in processability on moldingequipment, hence it is desired that the polymers shall be improved inmelt properties according to the purpose for which they are used.

With the view of improving the above-mentioned methods, Japanese PatentL-O-P Publns. Nos. 35006/1985 and 35008/1985 proposed a combination useof two or more kinds of metallocene compounds as the olefinpolymerization catalysts, and Japanese Patent L-O-P Publns. No.501369/1988 proposes a combination use of a metallocene compound andnon-metallocene compound as the olefin polymerization catalysts.However, none of these proposals are found yet to be whollysatisfactory.

Furthermore, the polymers, particularly copolymers obtained by the useof the above-mentioned olefin polymerization catalysts are low inmelting point and poor in heat resistance, hence it is desired saidpolymers or copolymers shall be improved in heat resistance.

On the one hand, ethylene copolymers obtained by the use of titaniumbased catalysts composed of a titanium compound and an organoaluminumcompound are excellent in heat resistance, but have such drawback thatwhen they are prepared so as to have a low density, the amount of theirhydrocarbon solvent-soluble portion becomes large and they exhibit pooranti-block properties.

OBJECT OF THE INVENTION

The present invention has been made in view of the prior art mentionedabove, and an object of the invention is to provide a method for thepreparation of ethylene polymer compositions which are excellent in meltproperties while retaining excellent characteristics of their own.

A further object of the invention is to provide a method for thepreparation of ethylene polymer compositions which are excellent inanti-block properties and heat resistance while retaining excellentcharacteristics of their own.

SUMMARY OF THE INVENTION

The first method for the preparation of ethylene polymer compositionsaccording to the present invention is characterized in that an ethylenepolymer composition having a density of 0.86-0.94 g/cm³ and an intrinsicviscosity of 1-6 dl/g is obtained by carrying out a multi-stage processcomprising

a polymerization step (a): wherein ethylene is polymerized or ethyleneand another α-olefin are copolymerized to form an ethylene polymer [I]having a density of higher than 0.88 g/cm³ and an intrinsic viscosity[η] of 0.3-3 dl/g, and

a polymerization step (b): wherein ethylene and another α-olefin arecopolymerized to form an ethylene copolymer [III] having a density nothigher than that of the ethylene polymer [I] and an intrinsic viscosity[η] of at least 1.5 times that of the ethylene polymer [I] and of 1-10dl/g, in the presence of an olefin polymerization catalyst [I] composedof a transition metal compound [A] containing a ligand having acycloalkadienyl skeleton and an organoaluminum oxy-compound [B] in sucha manner that the polymerization step (b) is carried out in the presenceof the polymerization product resulting from the polymerization step(a), or the polymerization step (a) is carried out in the presence ofthe polymerization product resulting from the polymerization step (b) sothat the amount of polymerization in the above-mentioned two steps shallassume the proportion in terms of part by weight of the ethylenecopolymer [II] to the ethylene polymer [I] being as 10-1000 to 100.

In accordance with the first method for the preparation of ethylenepolymer compositions of the invention, there can be obtained ethylenepolymer compositions excellent in melt properties.

The second method for the preparation of ethylene polymer compositionsaccording to the present invention is characterized in that an ethylenepolymer composition having a density of 0.87-0.93 g/cm³ and an intrinsicviscosity of 0.5-6 dl/g is obtained by carrying out a multi-stageprocess comprising

a polymerization step (c): wherein ethylene and another α-olefin arecopolymerized in the presence of an olefin polymerization catalyst [II]composed of a transition metal compound [A] containing a ligand having acycloalkadienyl skeleton and an organoaluminum oxy-compound [B] toobtain an ethylene copolymer [III] having a density lower than 0.91g/cm³ and an intrinsic viscosity [η] of 0.5-6 dl/g, and

a polymerization step (d): wherein ethylene, or ethylene and anotherα-olefin are polymerized or copolymerized in the presence of an olefinpolymerization catalyst [III] composed of a titanium catalyst component[C] containing titanium, magnesium and halogen as its essentialingredients, an organoaluminum compound [D] and/or an organoaluminumoxy-compound [E] to form an ethylene polymer [IV] having a densityhigher than that of the above-mentioned ethylene copolymer [III] and anintrinsic viscosity [η] of 0.5-6 dl/g, in such a manner that thepolymerization step (d) is carried out in the presence of the ethylenecopolymer [III] resulting from the polymerization step (c), or thepolymerization step (c) is carried out in the presence of the ethylenepolymer [IV] resulting from the polymerization step (d) so that theamount of polymerization in the above-mentioned two steps shall assumethe proportion in terms of part by weight of the ethylene polymer [IV]to the ethylene copolymer [III] being as 10-1000 to 100.

In accordance with the second method for the preparation of ethylenepolymer compositions of the present invention, there can be obtainedethylene polymer compositions excellent in anti-block properties andheat resistance despite the fact that they are low in density.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 (a) and FIG. 1 (b) are each a rough schematic drawingillustrating the first process for the preparation of ethylene polymercomposition of the present invention.

FIG. 2 is an IR spectrum of the benzene-insoluble organoaluminumoxy-compound.

FIG. 3 is an IR spectrum of the benzene-soluble organoaluminumoxy-compound.

FIG. 4 (a) and FIG. 4 (b) are each a rough schematic drawingillustrating the second process for the preparation of ethylene polymercomposition of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The first method for the preparation of ethylene polymer compositionsaccording to the present invention is illustrated below in detail.

In the first method for the preparation of ethylene polymer compositionsof the invention, the olefin polymerization catalyst [I] composed of thetransition metal compound [A] containing a ligand having acycloalkadienyl skeleton and the organoaluminum oxy-compound [B] isused.

FIG. 1 (a) and FIG. 1 (b) each show a rough schematic drawingillustrating the first process for the preparation of ethylene polymercompositions of the present invention.

First, the transition metal compound [A] containing a ligand having acycloalkadienyl skeleton used in the present invention is explained asfollows. This transition metal compound [A] is represented by theformula ML_(x) wherein M is a transition metal, L is a ligandcoordinating to the transition metal, at least one of L is a ligandhaving a cycloalkadienyl skeleton, and when at least two or more ligandshaving a cycloalkadienyl skeleton are contained, at least two ligandshaving a cycloalkadienyl skeleton may be linked together via alkylene,substituted alkylene, silylene or substituted silylene, L other than theligand having a cycloalkadienyl skeleton is a hydrocarbon group of 1-12carbon atoms, alkoxy of 1-12 carbon atoms, aryloxy having not more than12 carbon atoms, halogen or hydrogen, and x is a valence of thetransition metal.

In the above-mentioned formula, M which is a transition metal includeszirconium, titanium, hafnium, chromium or vanadium by preference, andparticularly preferred are zirconium and hafnium.

The ligands having a cycloalkadienyl skeleton include, for example,cyclopentadienyl, alkyl-substituted cyclopentadienyl such asmethylcyclopentadienyl, ethylcyclopentadienyl, n-butylcyclopentadienyl,t-butylcyclopentadienyl, dimethylcyclopentadienyl andpentamethylcyclopentadienyl, and indenyl and fluorenyl.

Two or more ligands having a cycloalkadienyl skeleton as mentioned abovemay coordinate to the transition metal and, in this case, at least twoligands having a cycloalkadienyl skeleton may be linked together viaalkylene, substituted alkylene, silylene or substituted silylene. Thealkylene group includes methylene, ethylene, trimethylene andtratramethylene, the substituted alkylene includes isopropylidene,tetramethylethylene, and the substituted silylene includesdimethylsilylene, ethylmethylsilylene and diphenylsilylene.

The ligand other than those having a cycloalkadienyl skeleton is ahydrocarbon group of 1-12 carbon atoms, an alkoxy group of 1-12 carbonatoms, an aryloxy group having not more than 12 carbon atoms, halogen orhydrogen.

The hydrocarbon group having 1-12 carbon atoms mentioned above includes,for example, alkyl, cycloalkyl, aryl and aralkyl, and the alkyl groupincludes methyl, ethyl, propoyl, isopropyl and butyl.

The cycloalkyl group mentioned above includes, for example, cyclopentyland cyclohexyl, the aryl group includes, for example, phenyl and tolyl,and the aralkyl group includes, for examples, benzyl and neophyl.

The alkoxy group mentioned above includes, for example, methoxy, ethoxyand butoxy, and the aryloxy group includes, for example, phenoxy.

The halogen mentioned above includes, for example, fluorine, chlorine,bromine and iodine.

Listed below are typical representatives of the transition metalcompounds having a cycloalkadienyl skeleton, represented by theaforementioned formula ML_(x) in which M is zirconium.

Bis(cyclopentadienyl)zirconium monochloride monohydride,

Bis(cyclopentadienyl)zirconium monobromide monohydride,

Bis(cyclopentadienyl)methyl zirconium hydride,

Bis(cyclopentadienyl)ethyl zirconium hydride,

Bis(cyclopentadienyl)phenyl zirconium hydride,

Bis(cyclopentadienyl)benzyl zirconium hydride,

Bis(cyclopentadienyl)neopentyl zirconium hydride,

Bis(methylcyclopentadienyl)zirconium monochloride hydride,

Bis(indenyl)zirconium monochloride monohydride,

Bis(cyclopentadienyl)zirconium dichloride,

Bis(cyclopentadienyl)zirconium dibromide,

Bis(cyclopentadienyl)methyl zirconium monochloride,

Bis(cyclopentadienyl)ethyl zirconium monochloride,

Bis(cyclopentadienyl)cyclohexyl zirconium monochloride,

Bis(cyclopentadienyl)phenyl zirconium monochloride,

Bis(cyclopentadienyl)benzyl zirconium monochloride,

Bis(methylcyclopentadienyl)zirconium dichloride,

Bis(dimethylcyclopentadienyl)zirconium dichloride,

Bis(n-butylcyclopentadienyl)zirconium dichloride,

Bis(indenyl)zirconium dichloride,

Bis(indenyl)zirconium dibromide,

Bis(cyclopentadienyl)zirconium dimethyl,

Bis(cyclopentadienyl)zirconium diphenyl,

Bis(cyclopentadienyl)zirconium dibenzyl,

Bis(cyclopentadienyl)zirconium methoxychloride,

Bis(cyclopentadienyl)zirconium ethoxychloride,

Bis(methylcyclopentadienyl)zirconium ethoxychloride,

Bis(cyclopentadienyl)zirconium phenoxychloride,

Bis(fluorenyl)zirconium dichloride,

Ethylenebis(indenyl)dimethyl zirconium,

Ethylenebis(indenyl)diethyl zirconium,

Ethylenebis(indenyl)diphenyl zirconium,

Ethylenebis(indenyl)methyl zirconium monochloride,

Ethylenebis(indenyl)ethyl zirconium monochloride,

Ethylenebis(indenyl)methyl zirconium monobromide,

Ethylenebis(indenyl)zirconium dichloride,

Ethylenebis(indenyl)zirconium dibromide,

Ethylenebis(4,5,6,7-tetrahydro-1-indenyl)dimethyl zirconium,

Ethylenebis(4,5,6,7-tetrahydro-1-indenyl)methyl zirconium monochloride,

Ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride,

Ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dibromide,

Ethylenebis(4-methyl-1-indenyl)zirconium dichloride,

Ethylenebis(5-methyl-1-indenyl)zirconium dichloride,

Ethylenebis(6-methyl-1-indenyl)zirconium dichloride,

Ethylenebis(7-methyl-1-indenyl)zirconium dichloride,

Ethylenebis(5-methoxy-1-indenyl)zirconium dichloride,

Ethylenebis(2,3-dimethyl-1-indenyl)zirconium dichloride,

Ethylenebis(4,7-dimethyl-1-indenyl)zirconium dichloride,

Ethylenebis(4,7-dimethoxy-1-indenyl)zirconium dichloride,

Isopropylidene(cyclopentadienyl-fluorenyl)zirconium dichloride,

Isopropylidenebis(indenyl)zirconium dichloride,

Dimethylsilylenebis(cyclopentadienyl)zirconium dichloride,

Dimethylsilylenebis(methylcyclopentadienyl)zirconium dichloride, and

Dimethylsilylenebis(indenyl)zirconium dichloride.

There may also be used transition metal compounds obtained by replacingthe zirconium metal in the above-exemplified zirconium compounds withtitanium metal, hafnium metal, or vandium metal.

Next, the organoaluminum oxy-compound [B] is explained below. Thisorganoaluminum oxy-compound [B] may be known aluminoxane or abenzene-insoluble organoaluminum oxy-compound first discovered by thepresent inventors.

The above-mentioned aluminoxane may be prepared, for example, by thefollowing procedures.

(1) The procedure for recovering aluminoxanes as their solution inhydrocarbons which comprises reacting organoaluminum compounds such astrialkylaluminum with suspensions in hydrocarbon solvents of compoundshaving absorbed water or salts containing water of crystallization, forexample, hydrates of magnesium chloride, copper sulfate, aluminumsulfate, nickel sulfate or cerous chloride.

(2) The procedure for recovering aluminoxanes as their solution inhydrocarbons which comprises allowing organoaluminum compounds such astrialkylaluminum to interact directly with water, ice or water vapor insolvents such as benzene, toluene, ethyl ether and tetrahydrofuran.

In this connection, the above-mentioned solution of aluminoxane maycontain a small amount of organometallic components. Furthermore, thesolution of aluminoxane recovered by the above-mentioned procedures maybe distilled to remove therefrom the solvent or unreacted organoaluminumcompound, followed by dissolving again in solvents.

The organoaluminum compounds used for preparing such solutions ofaluminoxane as mentioned above include, for example, trialkylaluminumsuch as trimethylaluminum, triethylaluminum, tripropylaluminum,triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum,tri-sec-butylaluminum, tri-tert-butylaluminum, tripentylaluminum,trihexylaluminum, trioctaylauminum, tridencylaluminum,tricyclohexylaluminum, tricyclooctylaluminum; dialkylaluminum halidessuch as dimethylaluminum chloride, diethylaluminum chloride,diethylaluminum bromide and diisobutylaluminum chloride; dialkylaluminumhydrides such as diethylaluminum hydride and diisobutylaluminum hydride;dialkylaluminum alkoxides such as dimethylaluminum methoxide anddiethylaluminum ethoxide; and dialkylaluminum aryloxides such asdiethylaluminum phenoxide.

Of the organoaluminum compounds as exemplified above, particularlypreferred is trialkylaluminum.

Furthermore, there may also be used as the organoaluminum compoundisoprenylaluminum represented by the general formula

    (i--C.sub.4 H.sub.9).sub.x Al.sub.y (C.sub.5 H.sub.10).sub.z

wherein x, y and z are each a positive number, and z≧2x.

The organoaluminum compounds mentioned above may be used either singlyor in combination.

Solvents used in the solutions of aluminoxane include aromatichydrocarbons such as benzene, toluene, xylene, cumene and cymeme;aliphatic hydrocabons such as pentane, hexane, heptane, octane, decane,dodecane, hexadecane and octadecane; alicyclic hydrocarbons such ascyclopentane, cyclohexane, cyclooctane and methylcyclopentane; petroleumfractions such as gasoline, kerosene and gas oil. In addition thereto,there may also be used ethers such as ethyl ether and tetrahydrofuran.Of these solvents as exemplified above, particularly preferred arearomatic hydrocarbons.

The benzene-insoluble organoaluminum oxy-compounds used in the firstprocess of the present invention contain an Al component which dissolvesin benzene at 60° C. in an amount of less than 10%, preferably less than5% and further desirably less than 2% in terms of Al atom, and it isinsoluble or sparingly soluble in benzene.

Solubility in benzene of such organoaluminum oxy-compounds as mentionedabove is obtained by suspending in 100 ml of benzene the organoaluminumoxy-compound in an amount correspond to 100 mg atoms in terms of Alatom, mixing the resulting suspension at 60° C. for 6 hours, filteringthe resulting mixture with G-5 glass filter equipped with a jacket keptat 60° C., and washing four times the solids portion separated on thefilter with 50 ml of benzene at 60° C. to measure the amount (× mmol) ofAl atoms present in the whole filtrate.

When the benzene-insoluble organoaluminum oxy-compounds of the presentinvention are analyzed by infrared spectrophotometry (IR), a ratio(D₁₂₆₀ /D₁₂₂₀) of an absorbance (D₁₂₆₀) at around 1260 cm⁻¹ to anabsorbance (D₁₂₂₀) at around 1220 cm⁻¹ is preferably less than 0.09,more preferably less than 0.08 and particularly in the range of from0.04 to 0.07.

Infrared spectrophotometric analysis of the organoaluminum oxy-compoundsas referred to in the present specification is carried out in thefollowing manner.

First, the organoaluminum oxy-compound is ground, together with nujol,in a nitrogen box to paste.

Next, the paste-like sample thus obtained is put between KBr plates, andIR spectrum is measured in a nitrogen atmosphere by means of IR-810manufactured and sold by Nippon Bunko K.K.

IR spectrum of the organoaluminum oxy-compound according to the firstprocess of the present invention as obtained is shown in FIG. 2.

From the thus obtained IR spectrum, a D₁₂₆₀ /D₁₂₂₀ ratio is sought, andthe ratio is obtained in the following manner.

(a) A line connecting a maximum point at around 1280 cm⁻¹ and a maximumpoint at around 1240 cm⁻¹ is taken as a base line L₁.

(b) A transmittance (T %) of an absorption minimum point at around 1260cm⁻¹ and a transmittance (T₀ %) of a point of intersection are read, thepoint of intersection being obtained by drawing a vertical line from theabsorption minimum point to a wave number abscissa axis (abscissa) andcrossing the vertical line with the base line L₁, wherein an absorbance(D₁₂₆₀ =log T₀ /T) is calculated.

(c) Similarly, a line connecting maximum points at around 1280 cm⁻¹ andat around 1180 cm⁻¹ is taken as a base line L₂.

(d) A transmittance (T' %) of an absorption minimum point at around 1220cm⁻¹ and a transmittance (T'₀ %) of a point of intersection are read,the point of intersection being obtained by drawing a vertical line fromthe absorption minimum point to a wave number abscissa axis (abscissa)and crossing the vertical line with the base line L₂, whereby anabsorbance (D₁₂₂₀ =log T'₀ /T') is calculated.

(e) From these values as obtained, D₁₂₆₀ /D₁₂₂₀ is calculated.

IR spectrum of a known benzene-soluble organoaluminum oxy-compound isshown in FIG. 3. As can be seen from FIG. 3, the benzene-solublealuminum oxy-compound has a value of D₁₂₆₀ /D₁₂₂₀ of being virtually0.10-0.13, and thus the benzene-insoluble organoaluminum oxy-compound ofthe present invention is apparently different in value of D₁₂₆₀ /D₁₂₂₀from the known benzene-soluble organoaluminum oxy-compound.

The benzene-insoluble organoaluminum oxy-compounds used in the presentinvention are presumed to have an alkyloxyaluminum unit represented bythe formula ##STR1## wherein R¹ is a hydrocabon group of 1 to 12 carbonatoms.

In the above-mentioned alkyloxyaluminum unit, R¹ includes, for example,methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, pentyl, hexyl,octyl, decyl, cyclohexyl and cyclooctyl. Of these hydrocarbon groupsexemplified above, preferred are methyl and ethyl, and particularlypreferred is methyl.

In addition to the alkyloxyaluminum unit of the formula ##STR2## thebenzene-insoluble organoaluminum oxy-compounds of the present inventionmay contain an oxyaluminum unit represented by the formula ##STR3##wherein R¹ is as defined above, and R² is a hydrocarbon group of 1 to 12carbon atoms, an alkoxyl group of 1 to 12 carbon atoms, an aryloxy groupof 6 to 20 carbon atoms, a hydroxyl group, halogen or hydrogen, providedthat R¹ and R² are different from each other. In that case, theorganoaluminum oxy-compounds desirably contain the alkyloxyaluminum unit##STR4## in a proportion of a least 30 mol %, preferably at least 50 mol% and particularly at least 70 mol %.

The processes for preparing the benzene-insoluble organoaluminumoxy-compounds of the present invention are illustrated below in detail.

The benzene-insoluble organoaluminum oxy-compounds are obtained bybringing a solution of aluminoxane into contact with water or activehydrogen containing compounds.

The active hydrogen containing compounds include alcohols such asmethanol, ethanol, n-propanol and isopropanol; diols such as ethyleneglycol and hydroquinone; and organic acids such as acetic acid andpropionic acid. Of these compounds, preferred are alcohols and diols,and especially preferred are alcohols.

Water or the active hydrogen containing compounds with which thesolution of aluminoxane is brought into contact may be used as solutionsor dispersions in hydrocarbon solvents such as benzene, toluene andhexane, ether solvents such as tetrahydrofuran or amine solvents such astriethylamine, or may be used in the form of vapor or solid. The waterwith which the solution of aluminoxane is brought into contact may bewater of crystallization of salts such as magnesium chloride, magnesiumsulfate, copper sulfate, nickel sulfate, iron sulfate and cerouschloride, or absorbed water absorbed to inorganic compounds such assilica, alumina and aluminum hydroxide or polymers.

Reaction of the solution of aluminoxane with water or the activehydrogen containing compounds is carried out usually in solvents, forexample, hydrocarbon solvents. The solvents used in this case arearomatic hydrocarbons such as benzene, toluene, xylene, cumene andcymene; aliphatic hydrocarbons such as pentane, hexane, heptane, octane,decane, dodecane, hexadecane and octadencane; alicyclic hydrocarbonssuch as cyclopentane, cyclohexane, cyclooctane and methylcyclohexane;petroleum fractions such as gasoline, kerosene and gas oil; halogenatedhydrocarbons such as halides of the above-mentioned aromatichydrocarbons, aliphatic hydrocarbons and alicyclic hydrocarbons,particularly, chlorides and bromides; and ethers such as ethyl ether andtetrhydrofuran. Of these solvents as exemplified above, particularlypreferred are aromatic hydrocarbons.

In the reaction as mentioned above, water or the active hydrogencontaining compound is used in an amount of 0.1-5 moles, preferably0.2-3 moles to 1 mole of Al atoms present in the solution ofaluminoxane. A concentration in terms of aluminum atom in the reactionsystem is desirably 1×10⁻³ -5 gram atom/l, preferably 1×10⁻² -3 gramatom/l, and a concentration of water in the reaction system is desirably2×10⁻⁴ -5 mol/l, preferably 2×10⁻³ -3 mol/l.

The solution of aluminoxane may be brought into contact with water orthe active hydrogen containing compound, for example, by the followingprocedures.

(1) A procedure which comprises bringing the solution of aluminoxaneinto contact with a hydrocarbon solvent containing water or the activehydrogen containing compound.

(2) A procedure which comprises blowing vapor of water or the activehydrogen containing compound into the solution of aluminoxane, therebybringing the aluminoxane into contact with the vapor.

(3) A procedure which comprises brining the solution of aluminoxane intocontact directly with water, ice or the active hydrogen containingcompound.

(4) A procedure which comprises mixing the solution of aluminoxane witha suspension of an absorbed water containing compound or a water ofcrystallization containing compound in hydrocarbon, or with a suspensionof a compound, to which the active hydrogen containing compound has beenabsorbed, in hydrocarbon, thereby bringing the aluminoxane into contactwith the absorbed water or water of crystallization.

The solution of aluminoxane may contain other components so long as theydo not exert adverse effects on the reaction of aluminoxane with wateror the active hydrogen containing compound.

The above-mentioned reaction of the solvent of aluminoxane with water orthe active hydrogen containing compound is carried out usually at -50°to 150° C., preferably 0°-120° C. and more desirably at 20°-100° C. Thereaction time employed is usually 0.5-300 hours, preferably 1-150 hours,though said reaction time varies largely depending upon the reactiontemperature used.

The benzene insoluble organoaluminum oxy-compound may also be preparedby direct contact of organoaluminum with water. In the reactionmentioned above, water is used in such amount that the organoaluminumatom dissolved in the reaction system is less than 20%, based on totalorganoaluminum atom.

Water with which the organoaluminum compound is brought into contact maybe used as solutions or dispersions in hydrocarbon solvents such asbenzene, toluene and hexane, ether solvents such as tetrahydrofuran oramine solvents such as triethylamine, or may be used in the form ofvapor or ice. The water with which the organoaluminum compound isbrought into contact may be water of crystallization of salts such asmagnesium chloride, magnesium sulfate, copper sulfate, nickel sulfate,iron sulfate and cerous chloride, or absorbed water absorbed toinorganic compounds such as silica, alumina and aluminum hydroxide orpolymers.

Reaction of the organoaluminum compound with water is carried outusually in solvents, for example, hydrocarbon solvents. The solventsused in this case are aromatic hydrocarbons such as benzene, toluene,xylene, cumene and cymene; aliphatic hydrocarbons such as pentane,hexane, heptane, octane, decane, dodecane, hexadecane and octadencane;alicyclic hydrocarbons such as cyclopentane, cyclohexane, cyclooctaneand methylcyclohexane; petroleum fractions such as gasoline, keroseneand gas oil; halogenated hydrocarbons such as halides of theabove-mentioned aromatic hydrocarbons, aliphatic hydrocarbons andalicyclic hydrocarbons, particularly, chlorides and bromides; and etherssuch as ethyl ether and tetrahydrofuran. Of these solvents asexemplified above, particularly preferred are aromatic hydrocarbons.

A concentration of organoaluminum compound in the reaction system interms of aluminum atom is desirably 1×10⁻³ -5 gram atom/l, preferably1×10⁻² -3 gram atom/l, and a concentration of water in the reactionsystem is desirably 1×10⁻³ -5 mol/l, preferably 1×10⁻² -3 mol/l.

In the reaction mentioned above, the organoaluminum atom dissolved inthe reaction system is less than 20%, preferably less than 10%, morepreferably 0 to 5% based on total organoaluminum atom.

The organoaluminum compound may be brought into contact with water, forexample, by the following procedures.

(1) A procedure which comprises bringing the hydrocarbon solution oforganoaluminum into contact with a hydrocarbon solvent containing water.

(2) A procedure which comprises blowing vapor of water into thehydrocarbon solution of organoaluminum, thereby bringing theorganoaluminum into contact with the vapor.

(3) A procedure which comprises mixing the hydrocarbon solution oforganoaluminum with a suspension of an absorbed water containingcompound or a water of crystallization containing compound inhydrocarbon, thereby bringing the organoaluminum into contact with theabsorbed water or water of crystallization.

(4) A procedure which comprises bringing the hydrocarbon solution oforganoaluminum into contact directly with ice.

The hydrocarbon solution of organoaluminum may contain other componentsso long as they do not exert adverse effects on the reaction oforganoaluminum with water.

The above-mentioned reaction of the organoaluminum with water is carriedout usually at -100° to 150° C., preferably -70° to 100° C. and moredesirably at -50° to 80° C. The reaction time employed is usually 1 to200 hours, preferably 2 to 100 hours, though the reaction time varieslargely depending upon the reaction temperature used.

The first series of olefin polymerization catalysts according to thefirst method of the invention, if necessary, may contain anorganoaluminum [C].

The organoaluminum compound [C] used herein includes such organoaluminumcompounds, for example, as represented by the formula R⁶ _(n) AlX_(3-n)wherein R⁶ is hydrocarbon of 1-12 carbon atoms, X is halogen orhydrogen, and n is 1-3.

In the above-mentioned formula, R⁶ is hydrocarbon of 1-12 carbon atoms,for example, alkyl, cycloalkyl or aryl, including concretely methyl,ethyl, n-propyl, isopropyl, isobutyl, pentyl, hexyl, octyl, cyclopentyl,cyclohexyl, phenyl, tolyl, etc.

The above-mentioned organoaluminum compounds will be exemplified below.

Trialkylaluminum such as trimethylaluminum, triethylaluminum,triisopropylaluminum, triisobutylaluminum, trioctylaluminum,tri-2-ethylhexylaluminum, etc.

Alkenylaluminum such as isoprenylaluminum, etc.

Dialkylaluminum halide such as dimethylaluminum chloride,diethylaluminum chloride, diisopropylaluminum chloride,diisobutylaluminum chloride, dimethylaluminum bromide, etc.

Alkylaluminum sesquihalides such as methylaluminum sesquichloride,ethylaluminum sesquichloride, butylaluminum sesquichloride,ethylaluminum sesquibromide, etc.

Alkylaluminum dihalides such as methylaluminum dichloride, ethylaluminumdichloride, isopropylaluminum dichloride, ethylaluminum dibromide, etc.

Alkylaluminum hydrides such as diethylaluminum hydride,di-isobutylaluminum hydride, etc.

Furthermore, there may also be used other organoaluminum compoundsrepresented by the formula R⁶ _(n) AlY_(3-n) wherein R⁶ is as definedpreviously, Y is --OR⁷, --OSiR⁸ ₃, --OAlR⁹ ₂, --NR¹⁰ ₂, --SiR¹¹ ₃ or##STR5## n is 1-2, R⁷, R⁸, R⁹ and R¹³ are each methyl, ethyl, isopropyl,isobutyl, cyclohexyl or phenyl, R¹⁰ is hydrogen, methyl, ethyl,isopropyl, phenyl or trimethylsily, R¹¹ and R¹² are each methyl orethyl.

The organoaluminum compounds as mentioned above include, for example,such compounds as enumerated below.

(i) Compounds of the formula R⁶ _(n) Al(OR⁷)_(3-n) such asdimethylaluminum methoxide, diethylaluminum ethoxide, diisobutylaluminummethoxide, etc.

(ii) Compounds of the formula R⁶ _(n) Al(OSiR⁸ ₃)_(3-n) such as Et₂Al(OSiMe₃), (iso-Bu)₂ Al(OSiMe₃), (iso-Bu)₂ Al(OSiEt₃), etc.

(iii) Compounds of the formula R⁶ _(n) Al(OAlR⁹ ₂)_(3-n) such as Et₂AlOAlEt₂, (iso-Bu)₂ AlOAl(iso-Bu)₂, etc.

(iv) Compounds of the formula R⁶ _(n) Al(NR¹⁰ ₂)_(3-n) such as Me₂AlNEt₂, Et₂ AlNHMe, Me₂ AlNHEt, Et₂ AlN(Me₃ Si)₂, (iso-Bu)₂ AlN(Me₃Si)₂, etc.

(v) Compounds of the formula R⁶ _(n) Al(SiR₁₁ ₃)_(3-n) such as (iso-Bu)₂AlSiMe₃, etc.

(vi) Compounds of the formula ##STR6## such as ##STR7##

Of the organoaluminum compounds as exemplified above, preferred arethose of the formula R⁶ ₃ Al, R⁶ _(n) Al(OR⁷)_(3-n) and R⁶ Al(OAlR⁹₂)_(3-n), particularly those in which R⁶ is isoalkyl and n=2 aredesirable. These organoaluminum compounds may be used in combination oftwo or more.

In this connection, the olefin polymerization catalysts as mentionedabove may also be used after supporting them on a solid inorganiccompound such as silica, alumina, magnesium oxide or magnesium chloride,or on a solid organic compound such as polyethylene, polypropylene orpolystyrene.

In the first method of the present invention, ethylene polymers areprepared by a process divided into two stages, that is, thepolymerization steps (a) and (b) as mentioned previously.

In the polymerization step (a), ethylene is homopolymerized or ethyleneand another α-olefin are copolymerized to form an ethylene polymer [I]having a density of higher than 0.88 g/cm³, preferably 0.89-0.94 g/cm³and an intrinsic viscosity [η] of 0.3-3 dl/g, preferably 0.5-2 dl/g.

In this ethylene polymer [I], it is desirable that the relationshipbetween an amount (W) of the portion soluble at 23° C. in n-decane and adensity (D) satisfies the following equation.

    log W≦-50×D+46.4, preferably

    log W≦-50×D+46.3 and especially

    log W≦-50×D+46.2.

In the polymerization step (b), ethylene and other α-olefin arecopolymerized to form an ethylene copolymer [II]. Desirably, the densityof the ethylene copolymer [II] is not higher than that of the ethylenepolymer [I] obtained in the above-mentioned polymerization step (a), andis preferably lower by 0.005 g/cm³ than that of the ethylene polymer[I], and the intrinsic viscosity [η] of the ethylene copolymer [II] isat least 1.5 times, preferably 2-10 times that of the ethylene polymer[I], and is concretely 1-10 dl/g, preferably 1.5-7 dl/g.

Further, it is desirable that the relationship between a density D ofthe ethylene polymer [I], ethylene copolymer [II] or the whole polymerand a temperature T (°C.) showing the highest peak in an endothermiccurve to be measured by a differential scanning calorimeter satisfiesthe following expression.

    T<450×D-297, preferably

    T<500×D-344 and especially

    T=550×D-391.

The above-mentioned two polymerization steps (a) and (b) may be carriedout in any order. That is, the ethylene copolymer [II] may be formed bycarrying out the polymerization step (b) in the presence of the ethylenepolymer [I] resulting from the polymerization step (a) which is firstcarried out, or the ethylene polymer [I] may be formed by carrying outthe polymerization step (a) in the presence of the ethylene copolymer[II] resulting from the polymerization step (b) which is first carriedout. In either case, these two steps must be carried out successively.In other words, the polymerization to be carried out in the latter stagemust be carried out in the presence of the polymer formed by thepolymerization carried out in the former stage. In this case, it ispreferable in the latter polymerization step to use in succession thecatalyst used in the former polymerization step without addition of afresh catalyst, because there are obtained polymers in which thedevelopment of fish-eye has been minimized.

In practicing the polymerization steps (a) and (b), it is desirable toform the ethylene copolymer [II] in the polymerization step (B) so as toamount to 10-1000 parts by weight, preferably 20-500 parts by weightwhen the amount of the ethylene polymer [I] obtained in thepolymerization step (a) is taken as 100 parts by weight.

Further, the intrinsic viscosity [η] of the whole polymer (including theethylene polymer [I] and ethylene copolymer [II]) is 1-6 dl/g,preferably 1.2-4 dl/g, and the density thereof is 0.86-0.94 g/cm³,preferably 0.87-0.93 g/cm³ and especially 0.88-0.92 g/cm³. Furthermore,the (MFR₁₀ /MFR₂) ratio of MRF₁₀ as measured at 190° C. under a load of10 kg to MFR₂ as measured at 190° C. under a load of 2.16 kg is morethan 7, preferably from 8 to 40.

The density D of the ethylene polymer [I] or ethylene copolymer [II] asreferred to in the present invention was determined by means of adensity gradient tube using the strand obtained at the time of MFRmeasurement under a load of 2.16 kg which has been heated at 120° C. for1 hour, followed by gradual cooling up to room temperature over a periodof 1 hour.

The intrinsic viscosity [η] of the above-mentioned polymer was measuredat 135° C. in decalin. Further, the amount of n-decane-soluble portionof the above-mentioned polymer was determined in the following manner.

About 3 g of the copolymer as weighed is dissolved at 145° C. in 450 mlof n-decane, followed by gradual cooling up to 23° C. The solution isthen filtered to remove a portion of the copolymer insoluble in n-decanetherefrom, and the n-decane is distilled off from the filtrate, therebyobtaining an amount (percent by weight based on the whole copolymer) ofan n-decane soluble portion of the copolymer.

The density (D₂), intrinsic viscosity [η]₂ and amount (W₂) of thepolymer obtained in the second stage polymerization step were calculatedaccording to the following equations, respectively. ##EQU1## wherein[η]_(w), [η]₁ and [η]₂ represent an intrinsic viscosity of the wholepolymer, that of the polymer obtained in the first step and that of thepolymer obtained in the second step, respectively, and f₁ and f₂represent the amount of polymerization in the first step and that of thepolymerization in the second step, respectively, and f₁ +f₂ is 1.##EQU2## wherein D_(w), D₁ and D₂ represent a density of the wholepolymer, that of the polymer obtained in the first stage, and that ofthe polymer obtained in the second stage, respectively. ##EQU3## whereinW_(w), W₁ and W₂ represent the amount of n-decane soluble portion of thewhole polymer, that of the polymer obtained in the first stage, and thatof the polymer obtained in the second stage, respectively.

In the present invention, moreover, pre-polymerization of olefin mayalso be carried out prior to the polymerization steps (a) and (b) asmentioned above. This pre-polymerization can be carried out under mildconditions using a suspension of olefin and the above-mentioned catalystcomponent [I] in an inert hydrocarbon medium.

The inert hydrocarbon medium used in this case may include, for example,aliphatic hydrocarbons such as propone, butane, pentane, hexane,heptane, octane, decane, dodecane, kerosine, etc.; alicyclichydrocarbons such as cyclopentane, cyclohexane, methyl cyclopentane,etc.; aromatic hydrocarbons such as benzene, toluene, xylene, etc.;halogenated hydrocarbons such as ethylene chloride, chlorobenzene, etc.;or mixtures thereof. Of these inert hydrocarbon media as illustratedabove, particularly preferred are aliphatic hydrocarbons. Thepre-polymerization may be carried out by using the olefin as a medium ormay also be carried out in a state substantially free from a medium.

Olefins used in the pre-polymerization may be the same as or differentfrom those used in the main polymerization as will be mentioned later.Concretely, the olefin preferably used in the pre-polymerization isethylene.

The reaction temperature employed in carrying out the pre-polymerizationis usually from about -20° to +100° C., preferably from about -20° to+40° C.

In the pre-polymerization, a molecular weight modifier such as hydrogenmay also be used. The molecular weight modifier is desirably used insuch an amount that an intrinsic viscosity [η], as measured in decalinat 135° C., of the polymer obtained by the pre-polymerization becomesmore than about 0.2 dl/g, preferably from about 0.5 to 10 dl/g.

The pre-polymerization is desirably carried out in such a manner thatthe polymer is formed in an amount, based on 1 g of the above-mentionedsolid catalyst, of about 0.1-500 g, preferably about 0.3-300 g andespecially 1-100 g. If the pre-polymerization amount is made excessivelylarge, the production efficiency of the olefin polymer in the mainpolymerization sometimes decreases.

Usable as α-olefins other than ethylene in the first process of thepresent invention are those having 3-20 carbon atoms, for example,propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene,1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene,1-eicosene, cyclopentene, cycloheptene, norbornene,5-methyl-2-norbornene, tetracyclododecene,2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene, etc.

In addition to such α-olefins as exemplified above, there may also beused styrene, vinylcyclohexane, diene, etc.

In the first process of the present invention, the polymerization may becarried out by any of polymerization techniques, for example, liquidphase polymerization such as solution or suspension polymerization orgas phase polymerization.

The reaction temperature of olefin using the olefin polymerizationcatalyst [I] is usually from -50° to 200° C., preferably from 0° to 150°C. The polymerization pressure is usually from ordinary pressure to 100kg/cm², preferably from ordinary pressure to 50 kg/cm², and thepolymerization reaction may be carried out by any of the batchwise,semicontinuous and continuous methods. The molecular weight of theolefin polymer obtained may be modified by the presence in thepolymerization system of hydrogen or by changing the polymerizationtemperature employed.

In polymerizing olefin with the above-mentioned olefin polymerizationcatalyst [I], it is desirable to use the transition metal compound [A]containing a ligand having a cycloalkadienyl skeleton in an amount ofusually 10⁻⁵ -1 mmol, preferably 10⁻⁴ -0.1 mmol, the organoaluminumoxy-compound [B] in an amount of usually 0.01-10 mmol, preferably 0.02-5mmol, and the organoaluminum compound [C] in an amount of usually 0-10mmol, preferably 0.1-5 mmol, each based on 1 liter of the reactionvolume.

In the first process of the present invention, the olefin polymerizationcatalyst [I] may contain other components useful for olefinpolymerization in addition to the above-mentioned components.

Next, the second method for the preparation of ethylene polymercompositions according to the present invention is illustrated below indetail.

FIG. 4 (a) and FIG. 4 (b) are each a rough schematic drawingillustrating the second process for the preparation of ethylene polymercompositions of the invention.

The second method for the preparation of ethylene polymer compositionsof the invention comprises a polymerization step (c) and apolymerization step (d).

In the polymerization step (c), the olefin polymerization catalyst [II]composed of the transition metal compound [A] containing a ligand havinga cycloalkadienyl skeleton and the organoaluminum oxy-compound [B] isused.

In the polymerization step (c), ethylene and other α-olefin arecopolymerized with the olefin polymerization catalyst [II] to form anethylene copolymer [III] having a density of not more than 0.91 g/cm³,preferably 0.86-0.905 g/cm³ more preferably 0.87-0.90 g/cm³ and anintrinsic viscosity [η] of 0.5-6 dl/g, preferably 0.7-4 dl/g.

In the polymerization step (c), the other α-olefin used may includethose as used in the first method of the present invention.

This polymerization step (c) may be carried out by any of polymerizationtechniques, for example, liquid phase polymerization such as solutionpolymerization and suspension polymerization, and gas phasepolymerization.

The polymerization of olefin with the olefin polymerization catalyst[II] may be carried out in the same manner as in the first method of thepresent invention as mentioned previously.

In the polymerization step (d), the olefin polymerization catalyst [III]composed of the titanium catalyst component [C] containing titanium,magnesium and halogen as its essential ingredients, the organoaluminumcompound [D] and/or the organoaluminum oxy-compound [E] is used.

The titanium catalyst component [C] containing titanium, magnesium andhalogen as its essential ingredients contains further an electron donor,if necessary.

Titanium compound useful for the preparation of the solid titaniumcatalyst component [C] includes tetravalent titanium compounds usuallyrepresented by the formula Ti(OR)_(g) X_(4-g) (wherein R is ahydrocarbon group, X is halogen, and 0≦g≦4). More particularly, thesetitanium compounds include titanium tetrahalides such as TiCl₄, TiBr₄,and TiI₄ ;

alkoxytitanium trihalides such as Ti(OCH₃)Cl₃, Ti(OC₂ H₅)Cl₃, Ti(O n-C₄H₉)Cl₃, Ti(O iso-C₄ H₉)Cl₃, Ti(OC₂ H₅)Br₃, and Ti(O iso-C₄ H₉)Br₃ ;

alkoxytitanium dihalides such as Ti(OCH₃)₂ Cl₂, Ti(OC₂ H₅)₂ Cl₂, Ti(On-C₄ H₉)₂ Cl₂, and Ti(OC₂ H₅)₂ Br₂ ; trialkoxytitanium monohalides suchas Ti(OCH₃)₃ Cl, Ti(OC₂ H₅)₃ Cl, Ti(O n-C₄ H₉)₃ Cl and Ti (OC₂ H₅)₃ Br;and tetraalkoxytitanium such as Ti(OCH₃)₄, Ti(OC₂ H₅)₄, Ti(O n-C₄ H₉)₄,Ti(O iso-C₄ H₉)₄ and Ti(O 2-ethylhexyl)₄.

These titanium compounds may be used either singly or in admixture oftwo or more, and also they may be diluted, before use, with hydrocarboncompounds or halogenated hydrocarbon compounds.

Magnesium compounds useful for the preparation of the solid titaniumcatalyst component [C] used in the second process of the inventioninclude those having reducing ability and those having no reducingability.

The magnesium compounds having reducing ability as referred to hereininclude, for example, those having a magnesium-carbon bond ormagnesium-hydrogen bond. Concrete examples of such magnesium compoundsas having reducing ability include dimethylmagnesium, diethylmagnesium,dipropylmagnesium, dibutylmagnesium, diamylmagnesium, dihexylmagnesium,didecylmagnesium, ethylmagnesium chloride, jpropylmagnesium chloride,butylmagnesium chloride, hexylmagnesium chloride, amylmagnesiumchloride, butyl ethoxy magnesium, ethyl butyl magnesium, octyl butylmagnesium, butylmagnesium halide, etc. The magnesium compoundsexemplified above may be used singly, or may form complex compounds withorganoaluminum compounds as will be mentioned later, and they also maybe either liquid or solid.

Concrete examples of magnesium compounds having no reducing abilityinclude halogenated magnesium such as magnesium chloride, magnesiumbromide, magnesium iodide or magnesium fluoride; alkoxy magnesium halidesuch as methoxy magnesium chloride, ethoxy magnesium chloride,isopropoxy magnesium chloride, butoxy magnesium chloride or octoxymagnesium chloride; aryloxy magnesium halide such as phenoxy magnesiumchloride, methylphenoxy magnesium chloride or dimethylphenoxy magnesium;alkoxy magnesium such as ethoxy magnesium, isopropoxy magnesium, butoxymagnesium n-octoxy magnesium or 2-ethylhexoxy magnesium; and magnesiumcarboxylate such as magnesium laurate or magnesium stearate.

The magnesium compounds having no reducing ability exemplified above maybe compounds derived from the above-mentioned magnesium compounds havingreducing ability or compounds derived at the time of preparation of thecatalyst component. The magnesium compound having no reducing abilitymay be derived from the magnesium compounds having reducing ability, forexample, by bringing said magnesium compounds having reducing abilityinto contact with polysiloxane compounds, halogen containing silanecompounds, halogen containing aluminum compounds or compounds such asesters, alcohols, etc.

The magnesium compounds used in the second process of the invention mayalso be complex or composite compounds of the above-mentioned magnesiumcompounds with other metals, or mixtures thereof. Further, the magnesiumcompounds used herein may also be mixtures of two or more of thesecompounds mentioned above.

Of these magnesium compounds exemplified above, preferred are thosehaving no reducing ability, particularly halogen containing magnesiumcompounds. Of the halogen containing magnesium compounds, preferred aremagnesium chloride, alkoxy magnesium halide and aryloxy magnesiumhalide.

In preparing the solid titanium catalyst component [C], it is preferableto use an electron donor. Useful electron donors include alcohols,amines, amides, ethers, ketones, esters, nitriles, phosphines, stibines,arsines, phosphoramides, thioethers, thioesters, acid anhydrides, acidhalides, aldehydes, alcoholates, alkoxy(aryloxy)silanes and organicacids. Of these electron donors exemplified above, preferred arealcohols, amines, ethers, esters, acid anhydrides,alkoxy(aryloxy)silanes and organic acids.

The solid titanium catalyst component [C] may be prepared by bringingthe above-mentioned magnesium compound (or metallic magnesium), titaniumcompound and, if necessary, electron donor into contact with oneanother. In preparing the solid titanium catalyst components, there maybe employed the known method for the preparation of highly activetitanium catalyst components from magnesium compounds, titaniumcompounds and, if necessary, electron donors. The above-mentionedcomponents may be brought into contact with one another in the presenceof other reaction reagents, for example, silicon, phosphorus andaluminum.

Briefly illustrated below are several examples of the process for thepreparation of these solid titanium catalyst components.

In the following processes for the preparation of the solid titaniumcatalyst component [C] as will be illustrated below, the electron donoris used, but the use of the electron donor is not always necessary.

(1) A process wherein a magnesium compound or a complex compoundcomprising the magnesium compound and electron donor is allowed to reactwith the titanium compound in the liquid phase. In carrying out thisreaction, each reactant may be pretreated with a reaction assistant suchas the electron donor and/or an organoaluminum compound or a halogencontaining silicon compound. In this process, the above-mentionedelectron donor is used at least one time.

(2) A process wherein a liquid magnesium compound having no reducingability is allowed to react with a liquid titanium compound in thepresence of an electron donor, thereby separating out a solid magnesiumtitanium composite.

(3) A process wherein the reaction product obtained in the process (2)is allowed to react further with a titanium compound.

(4) A process wherein the reaction product obtained in the process (1)or (2) is allowed to react further with an electron donor and a titaniumcompound.

(5) A process wherein a solid product obtained by pulverizing amagnesium compound or a complex compound comprising a magnesium compoundand an electron donor in the presence of a titanium compound is treatedwith any of halogen, a halogen compound and an aromatic hydrocarbon. Incarrying out this process, the magnesium compound or the complexcompound comprising the magnesium compound and the electron donor may bepulverized in the presence of a pulverized assistant. Further, afterpulverizing the magnesium compound or the complex compound comprisingthe magnesium compound and the electron donor in the presence of thetitanium compound, the solid product obtained thereby is pretreated witha reaction assistant, followed by treatment with halogen or the like.The reaction assistant used herein includes an organoaluminum compoundor a halogen containing silicon compound. In this process, the electrondonor is used at least one time.

(6) A process wherein the compound obtained in the processes (1)-(4) istreated with halogen, a halogen compound or an aromatic hydrocarbon.

(7) A process wherein a contact reaction product of a metallic oxidewith dihydrocarbyl magnesium and a halogen containing alcohol is broughtinto contact with an electron donor and a titanium compound.

(8) A process wherein a magnesium compound such as magnesium salt of anorganic acid, alkoxy magnesium or aryloxy magnesium is allowed to reactwith an electron donor, a titanium compound and/or a halogen containinghydrocarbon.

(9) A process wherein a catalyst component contained in a hydrocarbonsolution at least comprising a magnesium compound, alkoxy titaniumand/or an electron donor such as alcohol or ether are allowed to reactwith a titanium compound and/or a halogen containing compound such as ahalogen containing silicon compound.

(10) A process wherein a liquid magnesium compound having no reducingability is allowed to react with an organoaluminum compound to separatea solid magnesium aluminum composite, followed by reaction with atitanium compound.

Of the above-mentioned processes (1) to (10) for the preparation of thetitanium catalyst component [C], preferred are the processes (1) to (4)and (10).

Further, there may be used a solution containing the mixture of a liquidmagnesium compound having no reducing ability and a titanium compound.

The amount of each of the above-mentioned components used in thepreparation of the solid titanium catalyst component [C] cannot beindiscriminately defined, because it varies according to the processemployed. For example, however, there may be used, based on 1 mole ofthe magnesium compound, the electron donor in an amount of about 0.01-20moles, preferably 0.05-10 moles, and the titanium compound in an amountof about 0.01-500 moles, preferably 0.05-300 moles.

The solid titanium catalyst component thus obtained contains magnesium,titanium, halogen and, if necessary, an electron donor, as its essentialingredients.

In the solid titanium catalyst component [C], Halogen/Ti (atomic ratio)is about 4-200, preferably about 5-100, the above-mentioned electrondonor/Ti (molar ratio) is about 0.1-50, preferably about 0.2-25, andMg/Ti (atomic ratio) is about 1-100, preferably about 2-50.

In comparison with commercially available halogenated magnesium, thesolid titanium catalyst component [C], contains halogenated magnesiumhaving small crystal size whose specific surface area is usually largerthan about 10 m² /g, preferably about 30-1000 m² /g and especially about50-800 m² /g. This solid titanium catalyst component [C] does notsubstantially change in composition when it is washed with hexane,because the above-mentioned components used in the titanium catalystcomponent [C] are integrated into an integrated catalyst component.

The processes for the preparation of such highly active titaniumcatalyst components [C] as mentioned above are disclosed, for example,in Japanese Patent L-O-P Publns, Nos. 108385/1975, 126590/1975,20297/1976, 28189/1976, 64586/1976, 2885/1976, 136625/1976, 87489/1977,100596/1977, 147688/1977, 104593/1977, 2580/1978, 40093/1978,40094/1978, 43094/1978, 135102/1980, 135103/1980, 152710/1980, 811/1981,11908/1981, 18606/1981, 83006/1983, 138705/1983, 138706/1983,138707/1983, 138708/1983, 138709/1983, 138710/1983, 138715/1983,23404/1985, 195108/1985, 21109/1986, 37802/1986 and 37803/1986.

The titanium catalyst component [C] preferably has a polymerizationactivity for ethylene of 200 g-polymer/mmol-titanium and preferably 500g-polymer/mmol-Titanium.

The organoaluminum compound [D] used herein include such organoaluminumcompounds, for example, as represented by the formula R⁶ _(n) AlX_(3-n)wherein R⁶ is a hydrocarbon of 1-12 carbon atoms, X is halogen orhydrogen, and n is 1-3.

In the above-mentioned formula, R⁶ is hydrocarbon of 1-12 carbon atoms,for example, alkyl, cycloalkyl or aryl, including concretely methyl,ethyl, n-propyl, isopropyl, isobutyl, pentyl, hexyl, octyl, decyl,cyclopentyl, cyclohexyl, phenyl, tolyl, etc.

The above-mentioned organoaluminum compounds will be exemplified below.

Trialkylaluminum such as trimethylaluminum, triethylaluminum,triisopropylaluminum, triisobutylaluminum, trihexylaluminum,trioctylaluminum, tri-2-ethylhexylaluminum, etc.

Alkenylaluminum such as isoprenylaluminum, etc.

Dialkylaluminum halides such as dimethylaluminum chloride,diethylaluminum chloride, diisopropylaluminum chloride,diisobutylaluminum chloride, dimethylaluminum bromide, etc.

Alkylaluminum sesquihalides such as methylaluminum sesquichloride,ethylaluminum sesquichloride, isopropylaluminum sesquichloride,butylaluminum sesquichloride, ethylaluminum sesquibromide, etc.

Alkylaluminum dihalides such as methylaluminum dichloride, ethylaluminumdichloride, isopropylaluminum dichloride, ethylaluminum dibromide, etc.

Alkylaluminum hydrides such as diethylaluminum hydride,di-isobutylaluminum hydride, etc.

Furthermore, there may also be used other organoaluminum compoundsrepresented by the formula R⁶ _(n) AlY_(3-n) wherein R⁶ is as definedpreviously, Y is --OR, --OSiR⁸ ₃, --OAlR⁹ ₂, --NR¹⁰ ₂, --SiR¹¹ ₃ or##STR8## n is 1-2, R⁷, R⁸, R⁹ and R¹³ are each methyl ethyl, isopropyl,isobutyl, cyclohexyl or phenyl, R¹⁰ is hydrogen, methyl, ethyl,isopropyl, phenyl or trimethylsilyl, R¹¹ and R¹² are each methyl orethyl.

The organoaluminum compounds as mentioned above include, in concrete,such compounds as enumerated below.

(i) Compounds of the formula R⁶ _(n) Al(OR⁷)_(3-n) such asdimethylaluminum methoxide, diethylaluminum ethoxide, diisobutylaluminummethoxide, etc.

(ii) Compounds of the formula R⁶ _(n) Al(OSiR⁸ ₃)_(3-n) such as Et₂Al(OSiMe₃), (iso-Bu)₂ Al(OSiMe₃), (iso-Bu)₂ Al(OSiEt₃), etc.

(iii) Compounds of the formula R⁶ _(n) Al(OAlR⁹ ₂)_(3-n) such as Et₂AlOAlEt₂, (iso-Bu)₂ AlOAl(iso-Bu)₂, etc.

(iv) Compounds of the formula R⁶ _(n) Al(NR¹⁰ ₂)_(3-n) such as Me₂AlNEt₂, Et₂ AlNHMe, Me₂ AlNHEt, Et₂ AlN(Me₃ Si)₂, (iso-Bu)₂ AlN(Me₃Si)₂, etc.

(v) Compounds of the formula R⁶ _(n) Al(SiR¹¹ ₃)_(3-n) such as (iso-Bu)₂AlSiMe₃, etc.

(vi) Compounds of the formula ##STR9## such as ##STR10##

Of the organoaluminum compounds as exemplified above, preferred arethose of the formula R⁶ ₃ Al, R⁶ _(n) Al (OR⁷)_(3-n) and R⁶ Al(OAlR⁹₂)_(3-n), particularly those in which R⁶ is isoalkyl and n=2 aredesirable. These organoaluminum compounds may be used in combination oftwo or more.

The organoaluminum oxy-compound [E] used in the polymerization step (d)is the same as the organoaluminum oxy-compound [B] used in thepolymerization step (c).

The polymerization step (d) may also be carried out by using the olefinpolymerization catalyst [III] containing the electron donor as mentionedabove in addition to the above-mentioned titanium catalyst component[C], organoaluminum compound [D] and/or organoaluminum oxy-compound [E].

In the polymerization step (d), using the above-mentioned olefinpolymerization catalyst [III], ethylene is homopolymerized or ethyleneand another α-olefin are copolymerized to form an ethylene polymer [IV]having a density higher than that of the above-mentioned ethylenecopolymer [III] formed in the polymerization step (c), preferably adensity of 0.90-0.94 g/cm³ and especially 0.91-0.93 g/cm³, and anintrinsic viscosity [η] of 0.5-6 dl/g, preferably 0.7-4 dl/g. In theethylene polymer [IV] thus formed, the amount of the portion soluble inn-decane at 23° C. is desirably 0.1-10%.

Usable as α-olefins other than ethylene in the polymerization step (d)are those as exemplified in the case of the polymerization step (c).

The polymerization step (d) may be carried out by any of polymerizationtechniques, for example, liquid phase polymerization such as solution orsuspension polymerization, or gas phase polymerization. Of thesepolymerization techniques, particularly preferred is solutionpolymerization.

The polymerization temperature of olefin using the above-mentionedolefin polymerization catalyst [III] is usually from 0° C. to 250° C.,preferably from 50° C. to 200° C. The polymerization pressure is usuallyfrom ordinary pressure to 100 kg/cm², preferably from ordinary pressureto 50 kg/cm², and the polymerization reaction may be carried out by anyof the batchwise, semi-continuous and continuous methods. The molecularweight of the olefin polymer obtained may be modified by the presence ofhydrogen atoms or changing the polymerization temperature employed.

In polymerizing olefin with the above-mentioned olefin polymerizationcatalyst [III], it is desirable to use the titanium catalyst component[C] in an amount, based on 1 liter of the polymerization volume, ofusually about 10⁻⁴ -0.5 mmol, preferably about 10⁻³ -0.1 mmol in termsof Ti atom, the organoaluminum compound [D] in such an amount thataluminum atom becomes usually 1-2000 moles, preferably 5-500 moles basedon 1 mole of titanium atom, and the organoaluminum oxy-compound [E] insuch an amount that aluminum atom becomes usually 4-2000 moles,preferably 10-500 moles based on 1 mole of titanium atom.

The above-mentioned two polymerization steps (c) and (d) may be carriedout in any order. That is, the ethylene polymer [IV] may be formed bycarrying out the polymerization step (d) in the presence of the ethylenecopolymer [III] resulting from the polymerization step (c) first carriedout, or the ethylene copolymer [III] may be formed by carrying out thepolymerization step (c) in the presence of the ethylene copolymer [IV]resulting from the polymerization step (d) first carried out. In eithercase, these two steps must be carried out successively. In other words,the polymerization to be carried out in the latter stage must be carriedout in the presence of the polymer formed by the polymerization carriedout in the former stage. In the present invention, it is preferable tocarry out first the polymerization step (c), followed by thepolymerization step (d).

In practicing the polymerization steps (c) and (d), it is desirable toform the ethylene polymer [IV] in the polymerization step (d) so as toamount to 10-1000 parts by weight, preferably 20-500 parts by weightwhen the amount of the ethylene copolymer [III] obtained in thepolymerization step (c) is taken as 100 parts by weight.

Further, the intrinsic viscosity [η] of the whole polymer (including theethylene polymer [III] and ethylene copolymer [IV]) is 0.5-6 dl/g,preferably 0.7-4 dl/g, and the density of the whole polymer is 0.87-0.94g/cm³, preferably 0.88-0.93 g/cm³ and especially 0.89-0.92 g/cm³.

In the whole polymer as mentioned above, it is desirable that parts ofthe melt temperature curve as measured by means of DSC are observed at alevel of 110° C. or higher, preferably 115°-125° C., and therelationship between the amount of portion soluble in n-decane at 23° C.(Ww) and the density (Dw) satisfies logWw≦-50×Dw+45.9, preferablylogWw≦-50×Dw+45.8 and especially logWw≦-50×Dw+45.7.

The density D₁ of the ethylene polymer [III] or ethylene copolymer [IV]obtained in the polymerization step (c) of the first stage as referredto in the present specification was determined by means of a densitygradient tube using a strand obtained at the time of MFR measurementunder a load of 2.16 kg, the strand having been heat treated at 120° C.,for 1 hour, followed by gradual cooling to room temperature over aperiod of 1 hour.

The intrinsic viscosity [η] and the amount soluble in n-decane of theabove-mentioned polymer were measured in accordance with the methodillustrated already in the case of the first process of the presentinvention.

The copolymers are excellent in anti-block properties when they have asmaller amount soluble in n-decane.

The density (D₂), intrinsic viscosity [η]₂ and amount (W₂) soluble inn-decane of the polymer obtained in the polymerization step (d) of thesecond stage as referred to in the present specification were alsomeasured in the same manner as illustrated already in the case of thefirst process of the present invention.

A melting point of the copolymer as determined by means of DSC was usedas a measure of heat resistance of said copolymer.

In the second method of the present invention, the olefin polymerizationcatalyst [II] or [III] used may also contain other components useful forolefin polymerization in addition to the above-mentioned components. Thesame pre-polymerization as mentioned previously may also be carried outin the second method of the present invention prior to theabove-mentioned polymerization steps (c) and (d).

The present invention is illustrated below with reference to examples,but it should be construed that the invention is in now ay limited tothose examples.

EXAMPLE 1

(Preparation of organoaluminum oxy-compound [B])

A 400 ml glass flask thoroughly purged with nitrogen was charged with37.1 g of Al₂ (SO₄)₃.14H₂ O and 133 ml of toluene, cooled to -5° C., and47.9 ml of trimethylaluminum diluted with 152 ml of toluene was addeddropwise over a period of 1 hour, followed by reaction at a temperatureof from 0° to -5° C. for 1 hour. The temperature of the flask was thenelevated to 40° C. over a period of 3 hours, and the reaction wascontinued at that temperature for 72 hours. After completion of thereaction, the reaction mixture was subjected to solid-liquid separationby filtration, and the toluene was removed from the filtrate to obtain awhite solid organoaluminum oxy-compound.

(Polymerization)

A 2-liter stainless steel autoclave thoroughly purged with nitrogen wascharged with 900 ml of 4-methyl-1-pentene, followed by a rise intemperature of the system of up to 55° C. Into the autoclave were theninjected 1.0 mmol of triisobutylaluminum, 0.1 mg atom of theorganoaluminum oxy-compound in terms of aluminum atom and 0.001 mmol ofbis(methylcyclopentadienyl)zirconium dichloride together with ethyleneto initiate polymerization. The polymerization was carried out at thetotal pressure of 8 kg/cm² G and 60° C. for 10 minutes whilecontinuously feeding ethylene to the polymerization system [step (b)].Immediately after the 10-minute polymerization, 0.25 Nl of hydrogentogether with ethylene was injected into the autoclave to carry out thepolymerization at a total pressure of 12 kg/cm² G and 60° C. for 25minutes [step (a)]. The polymerization was stopped by the addition tothe polymerization system of small amounts of methanol, and theresulting polymer solution was poured into large amounts of methanol toseparate polymer therefrom. The polymer was then recovered and vacuumdried at 80° C. overnight. As a result, there was obtained 53.5 g of anethylene/4-methyl-1-pentene copolymer having [η] of 1.82 dl/g, a densityof 0.901 g/cm³, MFR₂ of 0.82 g/10 min, MFR₁₀ /MFR₂ of 10.5 a meltingpoint at 95° C. and an amount of portion of soluble in n-decane of 1.6%by weight.

Separately, only the above-mentioned step (b) was carried out. As aresult, there was obtained 15.5 g of an ethylene/4-methyl-1-pentenecopolymer having [η] of 3.30 dl/g, a density of 0.892 g/cm³, an amountof portion soluble in n-decane of 3.9% by weight and a melting point of87° C. From the results obtained in the above step (b), it was found bycalculation that the ethylene/4-methyl-1-pentene copolymer obtained inthe above step (a) amounted to 38.0 g, having [η] of 1.22 dl/g, adensity of 0.905 g/cm³ and an amount of portion soluble in n-decane of0.66% by weight.

COMPARATIVE EXAMPLE 1

(Polymerization)

Only the step (b) of Example 1 was repeated except that thepolymerization was carried out at 100° C. for 40 minutes and at thetotal pressure of 12 kg/cm² G, whereby 32.8 g of anethylene/4-methyl-1-pentene copolymer having [η] of 1.85 dl/g, a densityof 0.902 g/cm³, MFR₂ of 0.75 g/10 min, MFR₁₀ /MFR₂ of 6.0, a meltingpoint of 94° C., and an amount of portion soluble in n-decane of 1.1% byweight was obtained.

EXAMPLE 2

(Polymerization)

Immediately after completion of the step (b) of Example 1, the flask wascharged with 0.2 Nl of hydrogen to carry out polymerization at the totalpressure of 10 kg/cm² G and 60° C. for 25 minutes [step (a)].Thereafter, the same operation as in Example 1 was conducted to obtain44.3 g of an ethylene/4-methyl-1-pentene copolymer having [η] of 1.87dl/g, a density of 0.897 g/cm³, MFR₂ of 0.65 g/10 min, MFR₁₀ /MFR₂ of9.8, a melting point of 92° C., and an amount of portion soluble inn-decane of 2.4% by weight.

From the results obtained in the above step (a), it was found bycalculation that the ethylene/4-methyl-1-pentene copolymer obtained inthe step (a) amounted to 28.8 g, having [η] of 1.10 dl/g, a density of0.900 g/cm³ and an amount of portion soluble in n-decane of 1.6% byweight.

EXAMPLE 3

(Preparation of titanium catalyst component [C])

To a suspension of 1 mole of commercially available anhydrous magnesiumchloride in 2 liters of hexane was added dropwise with stirring in anitrogen atmosphere 6 moles of ethanol over a period of 1 hour, followedby reaction at room temperature for 1 hour. To the reaction mixture wasadded dropwise 2.6 moles of diethylaluminum chloride at roomtemperature, followed by stirring for 2 hours. After addition thereto of6 moles of titanium tetrachloride, the temperature of the system waselevated to 80° C., and the reaction was carried out with stirring atthat temperature for 3 hours. After completion of the reaction, solidsformed were separated from the reaction mixture, followed by repeatedwashing with hexane. To 200 ml of a decane suspension containing 5mmoles in terms of titanium atom of the thus obtained solid component(Ti: 3.4 wt %, Mg: 21 wt %) was added dropwise at room temperature 45.6mmoles of ethanol, followed by reaction at 90° C. for 1 hour. Aftercooling the system to room temperature, 15 mmoles of triethylaluminum,was added and reaction was carried out at room temperature for 1 hour toobtain the captioned titanium catalyst component [C].

(Preparation of organoaluminum oxy-compound [B])

A 400 ml glass flask thoroughly purged with nitrogen was charged with37.1 g of Al₂ (SO₄)₃.14H₂ O and 133 ml of toluene, cooled to -5° C., and47.9 ml of trimethylaluminum diluted with 152 ml of toluene was addeddropwise over a period of 1 hour, followed by reaction at a temperatureof from 0° to -5° C. for 1 hour. The temperature of the flask was thenelevated to 40° C. over a period of 3 hours, and the reaction wascontinued at that temperature for 72 hours. After completion of thereaction, the reaction mixture was subjected to solid-liquid separationby filtration, and the toluene was removed from the filtrate to obtain awhite solid benzene-soluble organoaluminum oxy-compound.

A 400 ml glass flask was charged with 58.4 ml of a solution of thebenzene-soluble organoaluminum oxy-compound obtained above in toluene(Al=2.57 mol/l), 90.5 ml of toluene and 25 g of Teflon columns (1.2 mmof length×2 mm of diameter). The temperature of the flask was cooled to5° C., and 1.08 ml of water was added dropwise over a period of 20minutes. In that case, the temperature inside the flask was maintainedat from 0° C. to -5° C. After completion of the dropwise addition ofwater the temperature of the flask was elevated up to 80° C. over aperiod of 30 minutes, and the reaction was carried out at thattemperature for 3 hours. Thereafter, the Teflon columns were removed bymeans of a 32-mesh screen from the reaction mixture to obtain abenzene-insoluble organoaluminum oxy-compound having a solubility inbenzene at 60° C. of 0.4 wt % and a D₁₂₆₀ /D₁₂₂₀ ratio as measured by IRof 0.053.

(Polymerization)

A 2-liter stainless steel autoclave thoroughly purged with nitrogen wascharged with 900 ml of 4-methyl-1-pentene, followed by rise intemperature of the system up to 75° C. Into the autoclave were theninjected 0.5 mmole of triisobutylaluminum, 0.1 mg atom in terms ofaluminum atom of the benzene-insoluble organoaluminum oxy-compound and0.001 mmole of bis(methylcyclopentadienyl)zirconium dichloride togetherwith ethylene to initiate polymerization. The polymerization was carriedout at the total pressure of 8 kg/cm².G and 80° C. for 40 minutes whilecontinuously feeding ethylene to the autoclave [step(c)]. Immediatelythereafter, 180 ml of the polymer solution obtained above was injectedtogether with ethylene into another autoclave having been used in thestep (c), and which had been charged with 800 ml of cyclohexane, 0.5 Nlof hydrogen and 0.3 mmole of ethylaluminum sesquichloride, and heated to170° C., and then 0.003 mg atom in terms of titanium atom of thetitanium catalyst component prepared above was injected thereintotogether with ethylene to initiate polymerization again. Thepolymerization was carried out at the total pressure of 25 kg/cm².G and170° C. for 15 minutes while continuously feeding ethylene to theautoclave [step (d)]. The polymerization was stopped by the addition tothe polymerization system of small amounts of methanol, and theresulting polymer solution was poured in large amounts of methanol toseparate polymer. The polymer was then recovered therefrom, and vacuumdried at 80° C. overnight. As a result, there was obtained 25.3 g of anethylene/4-methyl-1-pentene copolymer having [η] of 1.63 dl/g, a densityof 0.905 g/cm³, an amount of portion soluble in n-decane of 2.7wt %, anda peak of melting point, as measured by means of DSC, appearing at 122°,112° and 93° C.

Separately, only the step (c) mentioned above was repeated to recoverthe resulting polymer from 180 ml of the polymer solution obtainedthereby. As a result, there was obtained 9.6 g of anethylene/4-methyl-1-pentene copolymer having [η] of 1.80 dl/g, a densityof 0.891 g/cm³, an amount of portion soluble in n-decane of 4.3 wt %,and a melting point of 83° C. From the results obtained in this step(c), it was found by calculation that the ethylene/4-methyl-1-pentenecopolymer obtained in the step (d) mentioned above amounted to 15.7 g,having [η] of 1.53 dl/g, a density of 0.914 g/cm³, and an amount ofportion soluble in n-decane of 1.7 wt. %.

COMPARATIVE EXAMPLE 2

A 2-liter stainless steel autoclave thoroughly purged with nitrogen wascharged with 900 ml of 4-methyl-1-pentene, followed by a rise intemperature of the system to 90° C. Into the autoclave were injected 1.0mmole of triisobutylaluminum, 0.2 mg atom in terms of aluminum atom ofthe benzene-insoluble organoaluminum oxy-compound prepared in Example 3and 0.002 mmol of bis(cyclopentadienyl)zirconium dichloride togetherwith ethylene to initiate polymerization. The polymerization was carriedout at the total pressure of 20 kg/cm².G and 100° C. for 40 minuteswhile continuously feeding ethylene to the autoclave, whereby 91.0 g ofan ethylene/4-methyl-1-pentene copolymer having [η] of 1.56 dl/g, adensity of 0.907 g/cm³, an amount of portion soluble in n-decane of 0.65wt %, and a melting point of 97° C. was obtained.

COMPARATIVE EXAMPLE 3

A 2-liter stainless steel autoclave thoroughly purged with nitrogen wascharged with 200 ml of 4-methyl-1-pentene, 800 ml of cyclohexane and 0.5Nl of hydrogen, followed by a rise in temperature of the system to 160°C. Into the autoclave were then injected 0.35 mmole of ethylaluminumsesquichloride and 0.013 mg atom in terms of titanium atom of thetitanium catalyst component prepared in Example 3 together with ethyleneto initiate polymerization. The polymerization was carried out at thetotal pressure of 25 kg/cm².G and 170° C. for 40 minutes whilecontinuously feeding ethylene to the autoclave, whereby 115 g of anethylene/4-methyl-1-pentene copolymer having [η] of 1.40 dl/g, a densityof 0.908 g/cm³, an amount of portion soluble in n-decane of 3.9 wt %,and a melting point of 122.7°, 112.6° and 96° C. was obtained.

EXAMPLE 4

The step (d) of the polymerization of Example 3 was repeated except thatthe amount of the titanium catalyst used was changed to 0.005 mg atom interms of titanium atom, whereby 36.9 g of an ethylene/4-methyl-1-pentenecopolymer having [η] of 1.55 dl/g, a density of 0.907 g/cm³, an amountof portion soluble in n-decane of 2.5 wt % and a melting point of 122°,114° and 94° C. was obtained.

In this connection, it was found by calculation that theethylene/4-methyl-1-pentene copolymer obtained in the step (d) amountedto 27.3 g, having [η] of 1.46 dl/g, a density of 0.913 g/cm³ and anamount of portion soluble in n-decane of 1.9 wt %.

What is claimed is:
 1. A process for the preparation of an ethylenepolymer composition having a density of 0.88-0.92 g/cm³, an intrinsicviscosity (η) of 1.2-4 dl/g, a melt flow ratio MFR₁₀ /MFR₂ of from 8 to40 and, satisfying the relationship between density D and a temperatureT (°C.) showing the highest peak in an endothermic curve measured bydifferential scanning calorimetry (DSC) of T<450×D-297 said processcomprising(a) copolymerizing ethylene and an alpha-olefin having from 3to 20 carbon atoms in the presence of an olefin polymerization catalystcomprising (A) a transition metal compound having a cycloalkadienylskeleton and (B) an organoaluminum oxy-compound to form an ethylenecopolymer (II) having a density which is lower by at least 0.005 g/cm³than the density of the below-defined ethylene polymer (I), and anintrinsic viscosity (η) of from 1.5 to 7 dl/g and which is from 2 to 10times that of the below-defined ethylene polymer (I) and satisfying therelationship between density D of the copolymer (II) and a temperature T(°C.) thereof showing the highest peak in an endothermic curve measuredby DSC of T<450×D-297; and (b) polymerizing ethylene or copolymerizingethylene and an alpha-olefin of from 3 to 20 carbon atoms in thepresence of ethylene copolymer (II) obtained in step (a) and withoutaddition of fresh olefin polymerization catalyst, to obtain an ethylenepolymer (I) having a density of 0.88 g/cm³ to 0.94 g/cm³, an intrinsicviscosity (η) of 0.5 to 2.0 dl/g, and satisfying the relationshipbetween density D of the copolymer (I) and a temperature T (°C.) thereofshowing the highest peak in an endothermic curve measured by DSC ofT<450×D-297, and the relationship between density D of the copolymer (I)and an amount (W) of a portion thereof soluble at 23° C. in n-decane oflog W<-50×D+46.2, and wherein the amounts of ethylene polymer (I)produced in step (b) is such that the amount of ethylene copolymer (II)is from 10 to 1000 parts by weight based on 100 parts by weight ofethylene polymer (I).
 2. The method for the preparation of an ethylenepolymer composition according to claim 1, wherein the transition metalof the transition metal compound (A) is selected from the groupconsisting of zirconium, titanium, hafnium, chromium and vanadium. 3.The method for the preparation of an ethylene polymer compositionaccording to claim 1 wherein the transition metal of the transitionmetal compound (A) is zirconium.
 4. The method for the preparation of anethylene polymer composition according to claim 1 wherein the transitionmetal of the transition metal compound (A) is hafnium.
 5. The method forthe preparation of an ethylene polymer composition according to claim 1,wherein the amount of the ethylene copolymer (II) is 20-500 parts byweight based on 100 parts by weight of the ethylene polymer (I).
 6. Theprocess according to claim 1 wherein polymerization step (b) is carriedout in the presence of hydrogen gas.
 7. The process according to claim 6wherein polymerization step (b) is carried out under increased pressurerelative to polymerization step (a).
 8. A process for producing anethylene/4-methyl-1-pentene copolymer composition comprising(A)copolymerizing ethylene and 4-methyl-1-pentene in the presence of anolefin polymerization catalyst comprising triisobutylaluminum,organoaluminumoxy compound and bis(methylcyclopentadienyl) zirconiumdichloride under conditions yielding 100 parts by weight of anethylene/4-methyl-1-pentene copolymer (II) having an intrinsic viscosityof about 3.30 dl/g, a density of about 0.892 g/cm³, a melting point ofabout 87° C. and an amount of a portion soluble in n-decane at 23° C. ofabout 3.9% by weight; (B) copolymerizing ethylene and 4-methyl-1-pentenein the presence of the copolymer (II) and said olefin polymerizationcatalyst under conditions yielding from about 186 to about 245 parts byweight of an ethylene/4-methyl-1-pentene copolymer (I) having anintrinsic viscosity of from about 1.10 to about 1.22 dl/g, a density offrom about 0.900 to about 0.905 g/cm³ and an amount of a portion solublein n-decane at 23° C. of from about 0.66% to about 1.6% by weight, andwhereby the resulting ethylene/4-methyl-1-pentene copolymer compositioncomprising copolymer (I) and copolymer (II) has an intrinsic viscosityof from about 1.82 dl/g to about 1.87 dl/g, a density of from about0.897 to about 0.901 g/cm³, an MFR₂ of from about 0.65 g/10 min to about0.82 g/10 min, an MFR₁₀ /MFR₂ ratio of from about 9.8 to about 10.5, amelting point of from about 92° C. to about 95° C. and an amount ofportion soluble in n-decane at 23° C. of from about 1.6% by weight toabout 2.4% by weight.